• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 19
  • 14
  • 6
  • 5
  • 3
  • 2
  • Tagged with
  • 52
  • 52
  • 14
  • 13
  • 6
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Saproxylic Insect Communities in Boreal Mixedwoods of Northeastern Ontario as a Function of Variation in Woody Debris Quality and Quantity and Sampling Methods

Dennis, Robert William James 13 January 2010 (has links)
Saproxylic insects rely on dead or dying wood at some point in their development and appear to be sensitive to forest management. In 2005 and 2006, I sampled saproxylic insects in mixedwood boreal forests in northeastern Ontario to assess effects of: 1) different logging practices, 2) variations in woody debris (WD) qualities, and 3) different sampling methods. I also compared insect communities between heavily decayed WD and soil. Although I collected data on all arthropod orders, I focused on the families of the Diptera and parasitic Hymenoptera and the morphospecies of the Scelionidae and Diapriidae. These insects showed clear responses to the WD quality treatments, but not to the different logging treatments. A few families were affected by ex situ sampling. I also found that the faunas of soil and WD are rather distinct from each other. This study shows that WD is a source of forest biodiversity. Consequently, sustainable forest management will rely on studies like this to conserve and maintain the biodiversity of Canada's largest group of eco-zones.
12

Métodos de amostragem no levantamento da comunidade arbórea em floresta estacional semidecidual. / Sampling methods for surveying in tree species community in a semideciduous forest.

Mauricio Romero Gorenstein 26 April 2002 (has links)
Métodos de amostragem no levantamento da comunidade arbórea em floresta estacional semidecidual foram comparados. Primeiro foi testado o método de Bitterlich a fim de selecionar o fator de área basal mais adequado para o estudo da comunidade arbórea. O critério de inclusão adotado foi todas as árvores com DAP > 10 cm. Os fatores de área basal de 2, 3 e 4 m 2 ha -1 amostraram 596, 408 e 297 indivíduos e 59, 57 e 50 espécies, respectivamente. As estimativas de área basal, DAP médio, diversidade e equabilidade não apresentaram diferenças significativas. O fator de área basal igual a 3 foi selecionado porque mostrou melhor resultado em relação ao tempo gasto e facilidade de campo. Em uma segunda análise, os métodos de parcelas de área fixa (100 parcelas contíguas), pontos quadrantes e pontos de Bitterlich foram comparados para o levantamento da comunidade arbórea. O critério de inclusão adotado foi todas as árvores > 10cm. As 100 parcelas contíguas de 10x10m amostraram 59 espécies. Os 177 pontos de quadrantes amostraram 69 espécies e os 45 pontos de Bitterlich (fator de área basal = 3 m 2 ha -1 ) amostraram 57 espécies. Ocotea indecora foi favorecida pelo método de Bitterlich. O método de Bitterlich apresentou dificuldades no trabalho de campo devido a falta de visibilidade em algum pontos. Entretanto esse método apresentou melhor resultado na amostragem de espécies quando o esforço amostral é analisado por unidades amostrais. O método de quadrantes foi melhor na análise do esforço amostral por tempo. Na terceira análise o efeito de desvios da completa aleatoriedade espacial sobre a estimativa de densidade produzida pelo método de quadrantes foi analisada através de simulação de Monte Carlo. Foram geradas florestas hipotéticas com padrão espacial regular e agrupado com diferentes densidades. O efeito do tamanho da amostra também foi analisado, porém não mostrou efeito significativo na redução do viés. Os valores de viés relativo da estimativa da densidade variaram desde +70,3% (florestas regulares) até -75,7% (florestas fortemente agrupadas). A densidade de árvores não causou efeito na estimativa do viés, com exceção para as florestas completamente aleatórias e regulares em lattice aleatorizado. O método de quadrantes superestima a densidade arbórea para as florestas com padrão regular e subestima a densidade para as florestas com padrão espacial agrupado. É importante saber a priori o padrão espacial da floresta a fim de se aplicar o método de quadrantes e saber interpretar os seus resultados. / Sampling methods for surveying in tree species community in a semideciduos forest were compared. First was applied the angle count sampling method and select the best basal area factor to study the tree community. The criterion of inclusion adopted was all trees with DBH > 10cm. The basal factors 2, 3 and 4 m 2 ha -1 sampled 596, 408 and 297 individuals and 59, 57 and 50 species. The estimates of basal area, mean DBH, density, diversity and equability are not significantly differents among basal area factors. The basal area factor 3 was selected because showed better performance in terms of time spent and field operation. In a second analysis three sampling methods were compared for survey tree species community: fixed area plot (100 contiguos plots), point centered quarter method and Bitterlich method. The criterion of inclusion adopted was all trees with DBH > 10cm. The 100 contiguous plots of 10x10m showed 59 species. The 177 centered quarter method sampled 69 species and the 45 angle count points (basal area factor = 3 m 2 ha -1 ) showed 57 species. Ocotea indecora was favored by the Bitterlich method. Bitterlich method presented difficulty in field operation due to the lack of visibility in some sample points. However it better presented performance in the sampling of species in the amostral effort for plots. The centered quarter method was better in the amostral effort for time. In a third analysis the effect of deviation from the complete spatial randomness on point centered quarter method estimate of forest density was analysed through Monte Carlo simulation of hypothetical forests with regular and clustered spatial patterns and with diferent densities. The influence of sample size was also analysed, but showed no marked effect on estimation biases. The relative bias on the tree density estimation varied from +70.3% (regular lattice spatial pattern) to -75.7% (strongly clustered spatial pattern). Tree density did not affected estimation bias, except for completely spatial pattern and randomized regular lattice pattern. Point-centered quarter method overestimate (positive bias) tree density for regular patterns and underestimate (negative bias) for clustered patterns. Knowledge of tree spatial pattern in a forest is necessary for correct implementation and results interpretation in this method.
13

Métodos de amostragem e tamanho de amostra para avaliar o estado de maturação da uva Niágara Rosada / Sampling methods and sample size to evaluate the maturation state of the Ni´agara Rosada grape

Elton Gean Araújo 08 February 2008 (has links)
O Estado de São Paulo é o principal produtor de uvas de mesa do país, sendo a Niágara Rosada (Vitis Labrusca) a cultivar predominante. Para se oferecer produtos de qualidade ao mercado, os produtores necessitam determinar, periodicamente, o estado de maturação das uvas, sendo o teor de sólidos solúveis (tss), a principal variável avaliada. Para essa determinação, utilizase a amostragem dos frutos na área cultivada. O presente trabalho discute, assim, os métodos de amostragem estratificado e aleatório, e o tamanho adequado da amostra de baga individual, para avaliar o estado de maturação da uva Niágara Rosada, com base no teor de sólidos solúveis. O tamanho adequado da amostra de baga individual foi encontrado para os dois métodos de amostragem, separadamente, utilizando-se os métodos Máxima Curvatura, Máxima Curvatura Modificado e Curva da Variancia. Os métodos de amostragem foram comparados utilizando-se uma análise univariada para dados com medidas repetidas, através dos procedimentos GLM e MIXED do SAS. Foram utilizados dois procedimentos, para que se produzisse resultados confiáveis. Os tamanhos mínimos de amostra de baga individual requeridos, para os métodos estratificado e aleatório foram aproximadamente 30 e 27 bagas por área, respectivamente. Os métodos de amostragem estudados apresentaram diferença significativa, e o método aleatório apresentou grande variação máxima e mínima por planta, devendo assim, ser evitado para esse tipo de estudo. / Sao Paulo state is the main table grape producer in Brazil, being the Niágara Rosada (Vitis Labrusca) the predominant cultivar. To offer quality products to the market, the producers need to determine, periodically, the grapes maturation state, being the content of soluble solids the main variable measured. To determine this content, a sample of fruits in an area is collected. This work approaches the random and the stratified sampling methods and the appropriate sample size of individual berry to evaluate the maturation state of the Niágara Rosada based on the content of soluble solids. The appropriate sample size for individual berry was obtained for two sampling methods, separately, using the Maximum Curvature, Modified Maximum Curvature and Variance Curve methods. The sampling methods were compared using a univariate analysis for repeated measures data using the SAS GLM and MIXED procedures. Two different procedures were used to attain reliable results. The minimum berry sample size required for stratified and random methods were approximately 30 and 27 berries by area, respectively. The sampling methods investigated present significantly different results, and the random method presented high maximum and minimum variation by plant and should be avoided for this kind of study.
14

Conformational analysis of peptides and proteins for drug design using molecular simulations

Atzori, Alessio January 2015 (has links)
The intrinsic plasticity of biological systems provides opportunities for rational design of selective and potent ligands. Increasingly, computational methods are being applied to predict biomolecular flexibility. However, the motions involved in these processes can be large and occur on time scales generally difficult to achieve with standard simulation methods. In order to overcome the intrinsic limitations of classical molecular dynamics, this Ph.D. project focuses on the application of advanced sampling computational techniques to capture the plasticity of diverse biological systems. The first of these applications involved the evaluation of the secondary structure of the N-terminal portion of p53 and its inverse, reverse and retro-inverso sequences by using replica exchange molecular dynamics simulations in implicit solvent. In this study, we also evaluated the effects of reversal of sequence and stereochemistry in mimicking an inhibitory pharmacophoric conformation. The results showed how the ability to mimic the parent peptide is severely compromised by backbone orientation (for D-amino acids) and side-chain orientation (for reversed sequences). Moreover, the structural information obtained from simulations showed good agreement with NMR and circular dichroism studies, confirming the validity of the combination of replica exchange molecular dynamics with the ff99SB force field and Generalized Born solvent model for computational modelling of D-peptide conformations.In a second work, we explored conformations of the DFG motif of the p38α mitogen-activated protein (MAP) kinase. To achieve this, we employed an advanced sampling simulation method that has been developed in-house, called swarm-enhanced sampling molecular dynamics (sesMD). In contrast to multiple independent MD simulations, swarm-coupled sesMD trajectories were able to sample a wide range of DFG conformations, some of which map onto existing crystal structures. Simulated structures intermediate between DFG-in and DFG-out conformations were predicted to have druggable pockets of interest for structure-based ligand design. Overall, sesMD shows promise as a useful tool for enhanced sampling of complex conformational landscapes. Finally, we used microsecond MD simulations to evaluate the molecular plasticity of R-spondins, a class of proteins involved in the activation of the Wnt pathway. The unbound R-spondin 1 is characterised by a closed conformation, while, when complexed to proteins LGR and RNF43/ZNRF3, assumes an open and more extended arrangement. This is true also for R-spondin 2, in both its unbound or bound forms. From our simulation, we find that the closed R-spondin 1 conformation is stable, whilst, R-spondin 1 and 2 from their open conformation explore several intermediate structures. In addition, we evaluated the druggability of a potential binding site located at the interface between the second and the third β-hairpin moiety of the first furin domain. The computational screening with small molecular fragments provided interesting insights about the druggability and the pharmacophoric features of the potential binding pockets identified, outlining promising future perspectives of structure-based design of Wnt pathway inhibitors.
15

Investigation of Social Dysfunction and Affect in Schizophrenia

Danielle Margaret Beaudette (8894072) 15 June 2020 (has links)
<p>Social dysfunction is a hallmark of schizophrenia and leads to significant disability and distress. Decreased positive and increased negative affect predict poorer social functioning in those with schizophrenia. Social functioning and affect have traditionally been measured in the laboratory; yet, these methods are limited. Experience sampling methods (ESM) offer more immediate, ecologically valid assessments of these constructs. The purpose of this study was to examine social functioning and affect in schizophrenia using a novel form of ESM that passively collects audio data. The two primary hypotheses were: 1) clinical status (schizophrenia versus control) will predict social functioning, level of positive affect, and level of negative affect; and 2) the relationship between clinical status and affect will be moderated by context (social versus non-social). Additional exploratory aims tested the convergent validity between traditional, laboratory-based assessments of social functioning and this novel ESM. Data was collected from 38 people with schizophrenia and 36 control participants; Results partially supported the hypotheses. As expected, laboratory measures of social functioning revealed that those with schizophrenia performed worse than controls. ESM measures of social functioning found that the schizophrenia group interacted with others at the same rate as the control group but did not exhibit as much social engagement. ESM measures of affect revealed the schizophrenia group reported more negative affect than controls, but no differences in positive affect were found. Social context did not moderate the relationship between clinical status and affect. Lastly, correlations between laboratory measures and ESM measures of social functioning were significant for the schizophrenia group but not the control group. Results further our understanding of social functioning and affect in those with schizophrenia and yield important implications for future work.</p>
16

Compact Low-Cost Ultra-Wideband Pulsed-Radar System

Pitcher, Aaron D. January 2019 (has links)
Recently, the advent of the integrated circuits (ICs), the monolithic microwave integrated circuits (MMICs) and the multiprocessing computer technology have provided numerous opportunities to make the radar technology compact and affordable. The ultra-wideband (UWB) technology gives many advantages over the traditional narrowband radar systems due to its high spatial resolution, low susceptibility to interference, superior penetration depths, and increased peak power. However, the ability to digitize and reconstruct the full UWB signal spectrum comes at a considerable cost and size. Ultimately, high-speed sampling rates above 10 giga-samples per second (GSPS) are beyond the abilities of conventional analog-to-digital converters (ADCs). The UWB technology is inaccessible to the end-user for various advanced applications in microwave imaging and detection. The purpose of this work is to provide a low-cost, dual-channel UWB pulsed-radar system that is readily available with a 1:10 system bandwidth. The advancements in low-cost alternatives for compact and portable designs empower many promising UWB applications. Here, the desired bandwidth is from 500 MHz to 5 GHz, which utilizes a fast pulse repetition frequency (PRF) in short-range applications. The preliminary results from the novel Equivalent-Time Sampling Receiver are promising with an equivalent-time sampling rate up to 20 GSPS. Nevertheless, the system design is versatile for bandwidth tuning in order to meet the needs of different applications. This versatility is enabled by: i) selection of the effective sampling rate through the field-programmable gate array (FPGA) programming environment, ii) choice of the receivers' front-end track and hold (T & H) amplifier bandwidth, iii) a collection of different PRFs from the low kilohertz up to 20 MHz, iv) tuning of the pulse generator bandwidth, and v) simultaneous multi-channel capabilities enabling antenna beam-forming, polarization diversity and spatial diversity. The result is a fully functional prototype that costs a fraction of traditional bench-top solutions. / Thesis / Master of Applied Science (MASc)
17

Comparison of techniques for estimating pasture herbage mass and productive ground cover for Lakota prairie grass, Kentucky 31 endophyte free tall fescue, Kentucky 31 endophyte infected tall fescue and Quantum 542 tall fescue grazed by stocker steers

Rotz, Jonathan Daniel 12 June 2006 (has links)
In terms of acreage, forage is the number one crop in Virginia. The backbone of these forages has long been tall fescue (Lolium arundinaceum (Schreb.) S.J. Darbyshire). Knowledge of the plant species that make up a pasture and the relative amounts of each species present is important for interpreting potential animal performance. It is also important to know the relative amounts and types of weeds present and to monitor for the presence of poisonous plants or noxious weeds. An experiment was conducted in 2003 through 2005 to investigate botanical composition and yield of "Lakota" prairie grass (Bromus catharticus Vahl.), "Kentucky 31" endophyte-infected (KY31 E+), endophyte-free (KY31 E-), and "Quantum" tall fescue (non toxic endophyte infected) under grazing by stocker steers. Forage botanical composition and yield were determined by clipping three 0.25-m2 areas per treatment replicate. Prior to harvesting, the canopy height within each quadrate was measured with a disc meter. In 2005, productive ground cover was assessed using visual evaluation techniques, point quadrat method, and digital imagery quantified with terrestrial remote sensing. Forages were established September 2002 and grazing was initiated in July of 2003. Experimental design was a randomized complete block with four replications. Averaged over the three years the yield of KY31E+ was higher (p<0.05) than all other treatments. Lakota prairie grass had lower (p<0.05) yields than both KY31 E+ and Quantum tall fescue, however no yields did not differ between Lakota prairie grass and KY31 E-. Our results showed a typical forage distribution curve for all the treatments. Early spring, summer, and fall productivity of Lakota prairie grass was less than all the fescues, thus did not extend the grazing season. Forage persistence was greatest for KY31 E+ and Quantum and lowest for Lakota when averaged over all years. Among sampling methods for ground cover, terrestrial remote sensing was the most accurate, compared with visual evaluation and point quadrat methods. For estimates of all yield indirect methods of assessment had high errors; however the plate meter calibrated by sward density seemed the least variable of the methods tested. / Master of Science
18

Stochastic multi-market modeling with "efficient quadratures"

Oreamuno, Marco Antonio Artavia 17 February 2014 (has links)
Stochastische Anwendungen von großen Simulationsmodellen des Agrarsektors werden immer häufiger. Allerdings ist die stochastische Modellierung mit großen Marktmodellen rechenintensiv und mit hohen Kosten für Datenabspeicherung, -analyse und -manipulation verbunden. Gausssche Quadraturen sind effiziente Stichprobenmethoden, die wenige Punkte für die Approximation der zentralen Momente von gemeinsamen Wahrscheinlichkeitsverteilungen brauchen und somit die Kosten der Datenmanipulation senken. Für symmetrische Integrationsräume sind die Ecken des Oktaeder von Stroud (Stroud 1957) Formeln dritten Grades mit minimaler Anzahl von Punkten, die die stochastische Modellierung mit großen Modellen handhabbar machen kann. Es gibt trotzdem die Vermutung, dass Rotationen von Stroud''s Oktaeder einen Einfluss auf die Exaktheit der Quadraturen haben könnten; daher werden in dieser Studie acht unterschiedliche Rotationen (Quadraturformeln) getestet. Es zeigte sich, dass der Gebrauch der Formel von Artavia et al. (2009) oder der von Arndt (1996) bei der Generierung der Quadraturen entscheidend ist, und dass die Formel von Arndt einen höheren Exaktheitsgrad ergibt. Mit der Rotation, die sich aus der Formel von Arndt ergibt und Modellen oder Märkten mit starken Asymmetrien wie der Weizenmarkt in ESIM, könnten die Reihenfolge der stochastischen Variablen in der Kovarianz Matrix (A1 oder A2) oder die Methoden zur Einführung der Kovarianz Matrix (via Cholesky-Zerlegung –C– oder via die Diagonalisierungsmethode –D– ) einen bedeutsamen Einfluss auf die Exaktheit der Quadraturen haben. Mit Arndt''s Formel und weniger asymmetrischen Modellen oder Märkten, wie der Fall von Raps in ESIM, haben die Reihenfolgen A1 und A2 oder die Methoden zur Einführung der Kovarianz Matrix C und D weniger Einfluss auf die Exaktheit der Quadraturen. / Recently, stochastic applications of large-scale applied simulation models of agricultural markets have become more common. However, stochastic modeling with large market models incurs high computational and management costs for data storage, analysis and manipulation. Gaussian Quadratures (GQ) are efficient sampling methods requiring few points to approximate the central moments of the joint probability distribution of stochastic variables, and therefore reduce computational costs. For symmetric regions of integration, the vertices of Stroud''s n-octahedron (Stroud 1957) are formulas of degree 3 with minimal number of points, which can make the stochastic modeling with large economic models manageable. However, the conjecture exists that rotations of Stroud''s n-octahedron may have an effect on the accuracy of approximation of the model results. To address this, eight different rotations (quadrature formulas) were tested using the European Simulation Model (ESIM). It was found that using the formulas from Artavia et al. (2009) or Arndt (1996) in the generation of the quadratures is crucial, and furthermore, that the formula from Arndt yields higher accuracy. With the rotation obtained with Arndt''s formula and in models or markets with high asymmetries, as is the case for soft wheat in ESIM, the arrangement of the stochastic variables (A1 or A2) in the covariance matrix or the method selected to induce the covariance matrix (via Cholesky decomposition – C – or via the diagonalization method – D – ) may have a significant effect on the accuracy of the quadratures. With Arndt''s formula and with less asymmetric markets, as is the case for rapeseed in ESIM, the selection of arrangements A1 or A2 and of the method to induce the covariance C or D might not have a significant effect on the accuracy of the quadratures.
19

Censo fitossociológico, avaliação de métodos amostrais e dispersão de espécies arbóreas em fragmento de mata de cerrado / Phytosociological census, evaluation of sampling methods and dispersion of tree species in savannah fragment

Scalon Filho, Homero 04 April 2014 (has links)
Made available in DSpace on 2017-07-10T17:40:46Z (GMT). No. of bitstreams: 1 2014_Tese_Homero_Scalon_Filho.pdf: 7423772 bytes, checksum: da7fe41b8adc20ffaebc71dac1a85c5a (MD5) Previous issue date: 2014-04-04 / Limited information is available on the floristic composition of ecosystem and population surveys are time consuming and expensive, and sampling a considerable alternative. The objective of this work was the completion of the census of five native tree species in the forest area of savanah, and subsequent implementation and evaluation of sampling methods employed in phytosociological surveys. The characteristics of frequency, density and dominance absolutes were estimated and observed the dispersion of juveniles relative to the nearest matrix. An area of 75,000 m2 was previously selected in the Santa Madalena farm, district of Itahum, city of Dourados, MS, Brazil, located at coordinates 22o09'07.57" S and 54o59'55.43" O to 483 m high, and divided into 30 smaller areas of 50 x 50 meters to facilitate the identification, marking, counting, measuring and checking of tree evaluated. Species considered due to the high extraction for presenting therapeutic capabilities, were Anadenanthera falcata (Bth) Speg (angico-preto-do-cerrado), Bauhinia holophyla (Bong.) Stend (falsa-pata-de-vaca), Dimorfanda mollis Benth (faveiro-do-cerrado), Duguetia furfuraceae (St. Hil.) B. et H. (araticum-do-cerrado) and Tabebuia aurea (Manso) B. et H. (para-tudo). Were collected Circumference at Breast Height - CBH, canopy diameter and georeferenced position. The diameter of the canopy was estimated from the average of the largest diameter and the other transverse to it, allowing the estimation of the mean radius, which was then transformed into area pantries to estimate the coverage area CA of each species. The CBH was used for calculation of dominance parameter affect the basal area. The frequency was calculated as the number of individuals observed and the number of areas in which the species occurred, and the density was expressed as number of individuals per unit area (acres). Values of frequency, density and dominances relatives were used to calculate the Importance Value Index - IVI. The data georeferencing were launched in Software AutoCad generated six maps in scale 1:400, being a general map and five, one for each species evaluated. The maps were divided into quadrants for analysis of dispersion and sampling strategies from them were established with variation of the area sampled to evaluate the effectiveness of different sampling systems used in phytosociological surveys in forest savannah. 549 individuals were found with CBH above 0.02 m being the species with the highest number araticum (155 individuals), and falsa-pata-de-vaca the lowest occurrence (9 individuals). The CA was generated by five species of 922.959 m2 ha-1, this being 476.832 m2 ha-1 refers to angico and only 3.289 m2 ha-1 for the falsa-pata-de-vaca. The angico still showed higher dominance (1.212) and IVI (103.560), and falsa-pata-de-vaca only 0.003 of dominance and IVI of 5.22. CBH values were transformed in diameter at breast height - DBH and distributed into five classes in order to investigate their distribution according to age groups, and it was found that the class of younger subjects, there was suppression of the species, indicating strong impacting action and electing distribution in age classes as an important tool for understanding the phenological state of the forest. Treatments faced with the census sampling methods were composed of varying areas. Most methods differ significantly in phytosociological parameters of the sense performed. For the evaluation of the number of individuals para-tudo the method of sample plots was efficient. For estimates the phytosociological parameters any of sampling methods can be recommended for forest savannah, in the conditions that this study was conducted / Existe pouca informação sobre a composição florística dos ecossistemas e levantamentos populacionais são demorados e caros, sendo a amostragem uma alternativa considerável. O objetivo deste trabalho foi a realização do censo populacional de cinco espécies arbóreas em área nativa de mata de cerrado, e posterior aplicação e avaliação de métodos de amostragem empregados em levantamentos fitossociológicos. Foram estimadas as características frequência, densidade e dominância absolutas e observada a dispersão dos indivíduos jovens em relação à matriz mais próxima. Uma área útil de 75.000 m2 foi previamente selecionada na fazenda Santa Madalena, distrito de Itahum, município de Dourados, MS, situada nas coordenadas 22o09 07.57 S e 54o59 55.43 O a 483 metros de altitude, e dividida em 30 áreas menores de 50 x 50 metros para facilitar a identificação, marcação, contagem, medição e conferência dos indivíduos avaliados. As espécies consideradas em função do alto extrativismo, por apresentarem capacidades terapêuticas segundo mateiros locais, foram a Anadenanthera falcata (Bth) Speg (angico-preto-docerrado), Bauhinia holophyla (Bong.) Stend (falsa-pata-de-vaca), Dimorfanda mollis Benth (faveiro-do-cerrado), Duguetia furfuraceae (St. Hil.) B. et H. (araticum-do-cerrado) e Tabebuia aurea (Manso) B. et H. (para-tudo). Os dados coletados foram circunferência à altura do peito CAP, diâmetro de copas e posição georreferenciada. O diâmetro das copas foi estimado a partir da média entre o maior diâmetro e outro transversal a este, permitindo a estimativa do raio médio que em seguida foi transformado em área de copas para estimativa da área de cobertura AC de cada espécie. A CAP foi utilizada para os cálculos de dominância, parâmetro afeto à área basal. A frequência foi calculada em função do número de indivíduos observados e o número de áreas em que ocorreu a espécie, e a densidade foi expressa em número de indivíduos por unidade de área (hectares). Dos valores de frequências, densidades e dominâncias relativas foi calculado o Índice de Valor de Importância IVI. Os dados de georreferenciamento foram lançados no Software AutoCad que gerou seis mapas em escala de 1:400, sendo um mapa geral e outros cinco, um para cada espécie avaliada, que foram divididos em quadrantes para análises de dispersão e a partir deles foram estabelecidas estratégias amostrais, com variação da área amostrada visando avaliar a eficácia dos diferentes sistemas amostrais utilizados em levantamentos fitossociológicos em mata de cerrado. Foram encontrados 549 indivíduos com CAP acima de 0,02 m sendo a espécie com maior número o araticum (155 indivíduos), e a falsa-pata-de-vaca a de menor ocorrência (9 indivíduos). A AC gerada pelas cinco espécies foi de 922,959 m2 ha-1, sendo desta 476,832 m2 ha-1 referente ao angico e apenas 3,289 m2 ha-1 pela falsa-pata-de-vaca. O angico ainda apresentou maior dominância (1,212) e IVI (103,560), e a falsa-pata-de-vaca apenas 0,003 de dominância e IVI de 5,22. Os valores de CAP foram transformados em Diâmetro à Altura do Peito - DAP e distribuídos em cinco classes para averiguação de sua distribuição conforme grupos de idade, e foi verificado que na classe dos indivíduos mais jovens houve supressão das espécies, evidenciando forte ação impactante e elegendo a distribuição em classes de idades como ferramenta importante para o entendimento do estado fenológico da mata. Os tratamentos confrontados com o censo foram compostos por métodos amostrais com variação nas áreas. Para a avaliação do número de indivíduos do para-tudo os métodos foram eficientes exceção feita à parcela de 5 x 10 m e o transecto em duas direções. Os métodos diferiram significativamente, em todos os parâmetros fitossociológicos, do senso realizado. Para estimativas dos parâmetros fitossociológicos nenhum dos métodos amostrais avaliados pode ser recomendado para mata de cerrado, nas condições em que este estudo foi conduzido
20

Optimal stopping for event-triggered sensing and actuation

Rabi, Maben, Johansson, Karl Henrik, Johansson, Mikael January 2008 (has links)
Novel event-triggered sensing and actuation strategies are presented for networked control systems with limited communication resources. Two architectures are considered: one with the controller co-located with the sensor and one with the control co-located with the actuator. A stochastic control problem with an optimal stopping rule is shown to capture two interesting instances of these architectures. The solution of the problem leads to a parametrization of the control alphabet as piecewise constant commands. The execution of the control commands is triggered by stopping rules for the sensor. In simple situations, it is possible to analytically derive the optimal controller. Examples illustrate how the new event-based control and sensing strategies outperform conventional time-triggered schemes. / <p>© 2008 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. Qc 20120220</p>

Page generated in 0.4779 seconds